1. Field of the Invention
The present invention relates to a technology of liquid crystal display, and more particularly, to a display device including a circuitry of multiple V-By-One (VBO) inputs.
2. Description of Prior Art
In recent years, with the increased requirements of high definition screen of display devices, requirements of a signal transmission interface of display devices is also to be increased. Thus, V-By-One (VBO) becomes a standard signal transmission interface suitable flat panel displays, and with advantage in high transmission quality, high transmission speed, reducing cost, reducing installation space and so on. It is widely used in display devices, multifunction printers, office equipment, car entertainment equipment, robots, security systems and other fields. Especially in ultra-high-definition (UD) display devices, a VBO is generally used in interface between in a circuit board and a controlling board (e.g., a Timing-Control board).
VBO signal is a high-frequency differential signal, it does not have any individual clock signals, but transmits clock signals and data signals in different time respectively, and has a specific transmission mechanism. In the VBO transmission mechanism, first of all, a VBO output (e.g. a circuit board) can send the clock signals according to a fixed frequency to a VBO input (e.g. a controlling board.) Then, when a transmission frequency of data transmission from the VBO output is locked by the VBO input, the VBO input can send a lockup signal to the VBO output to inform the transmission frequency of data transmission has been locked, and the VBO output can transmit data signals according to the fixed frequency to the VBO input, so the VBO input can receive and grab data according to the fixed frequency. Here below, the clock signal can be a clock data recovery (CDR) training pattern.
FIG. 1 is an illustrational view of circuitry of multiple VBO inputs of a conventional display device. As shown in FIG. 1, a plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board are connected to the VBO output LOCK_TX of the circuit board through resistors, respectively. The VBO output LOCK_TX of the circuit board is connected to a power source VDD through a resistor.
When the power source (e.g., 3.3V) powered on, the lockup signal sent from the plurality of VBO inputs LOCK_RX1, LOCK_RX2 are treated as high frequency signals. When the lockup signals are high frequency signals, it indicates that the controlling board does not lockup the transmission frequency for data transmission. When the VBO output LOCK_TX of the circuit board received the high frequency signals, the VBO output LOCK_TX of the circuit board send then clock signals (e.g., CDR training pattern) to the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board. When the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board locked the transmission frequency for data transmission according to the clock signals, the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board reduce the frequency of the lockup signal (i.e., send a low frequency signal.) The lockup signal is a low frequency signal; it indicates that the controlling board has locked the transmission frequency for data transmission. When the VBO output LOCK_TX of the circuit board received the low frequency signals, the VBO output LOCK_TX of the circuit board sends data signals to the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board. If the controlling board lost the transmission frequency for data transmission, the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board can increase the lockup signal again, then the VBO output LOCK_TX of the circuit board can send the clock signals again.
The circuitry as shown in FIG. 1, Because the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board and the VBO output LOCK_TX of the circuit board are a short circuit to receive the clock signals and data signals from the VBO output LOCK_TX of the circuit board, therefore, if one of the VBO input lost the transmission frequency for data transmission, the high frequency lockup signal will be reduced by low frequency lockup signals sent from other VBO inputs. So the VBO output LOCK_TX of the circuit board cannot resend the clock signals, the VBO inputs which is lost the transmission frequency still receive data according to wrong frequency. In addition, when the power source powered on, the frequencies locked by the plurality of VBO inputs LOCK_RX1, LOCK_RX2, . . . , LOCK_RXn of the controlling board are not synchronized, it will also find the similar errors.